1. Field of the Invention
The present invention relates to an inner coupling electrodeless lamp, in particularly to an inner coupling tubular type electrodeless lamp.
2. Description of the Related Art
The conventional electrodeless lamp could be classified into two types in accordance with the structures and the means for power coupling. One of the classifications is the external coupling electrodeless lamp, and the other of the classifications is the inner coupling globe type electrodeless lamp. The light emitted from these two types of electrodeless lamps belongs to the surface light source. A tubular diameter of the external coupling electrodeless lamp is in fact not large. However, a discharging circuit of such fluorescent lamp should adopt a loop shape. Herein, an annular and close tube for such fluorescent lamp is formed. Nonetheless, the formation of either an annular tube or a rectangular tube for cooperating with the fixture exists in a certain difficulty. Moreover, a diameter of the bulb of the inner coupling globe type electrodeless lamp is rather large. Correspondingly, the design for a reflector cooperating with the lamp thereof is actually complicated. Herein, if a light distribution curve of such globe lamp is unavailable, a requirement for the light distribution of a street fixture of TYPE III is unable to be met. Additionally, only one end of the inner coupling globe type electrodeless lamp is designed open so that one end of the coupling cavity could be designed open. As a result, the other end of the globe lamp is accordingly designed close, and an inferior ventilating environment is incurred, so an unsatisfactory radiating effect is adversely caused. Consequently, the using life of the lamp is largely influenced. Herein, the inner coupling globe type electrodeless lamp is in fact monotonous, and so is its practical adopting environment. Therefore, an inner coupling tubular type electrodeless lamp is disclosed in the market.
An inner coupling tubular type electrodeless lamp with two ends thereof is disclosed by the same applicant as that of the present invention. The publication no. of afore disclosure is CN1560898 (U.S. Pat. No. 6,940,232 B1 Filed Feb. 27, 2004), and the publication date is Jan. 5, 2005. The electrodeless lamp has an airtight glass holder with a ventilating shaft disposed thereon. Namely, a coupling cavity of the disclosure is designed by the disposition of two open ends (as shown in claim 9 and FIG. 6 of the disclosure). Thereby, the air is convected within the ventilating shaft. Moreover, dual conducting posts provide a satisfactory heating scattering effect. Thus, the heat generated in the bulb could be efficiently dispersed. Such disclosure solves the existing heat conducting problem in the bulb.
However, a ratio of the surface area of the inner portion to the external surface of the bulb is in fact not small in either the inner coupling globe type electrodless lamp or the inner coupling tubular type electrodeless lamp that is designed with two open ends. That is to say, the light emitted from the fluorescent powder on the inner portion can not be well utilized, so that the influenced illuminant performance still adversely exists.